One of the main mechanisms involved inhe is here who sees Pass under another plate to be recycled inside . Subduction zones are generally associated with intense , often of the explosive type. In addition, most of the current mountain ranges, Or the Himalayas, as a result of a continental collision that followed the closure of an ocean by a subduction zone. Thus, these mountain ranges contain many clues that allow us to indirectly study the complex mechanism of subduction zones.
The mantle absorbs large amounts of water in subduction zones
Many parameters are triggered and their diversity makes each subduction zone a unique dynamic system.
One of these factors is water. It is indeed an essential element that will directly affect the mantle fusion ability andbut also behavior while going up and .
It has long been known that subduction zones represent high humidity environments. When submerged in the mantle, the fused plate carries an enormous amount ofSaturated oceans. This water will significantly moisten the mantle rocks and directly affect the formation of magma. The Issued by On the roof bear the signature of this which will also define the style . more of It is more moisturized . This explains why .
Finding the initial water content of magma is a complex problem
So far, analysis of igneous rocks indicates that, in this subduction context, the mantle contains about 4% water (per unit weight). However, a new study questions this value, and puts forward the idea that the signature in igneous rocks would not represent the actual water content of the primary magma. For the authors of the study published inIt does seem likely that some processes – either at the time of the rapid rise of the magma, or as it reaches the surface – somehow mask the original water content of the magma. Magmatic.
To try to find the exact value of the amount of water, the research team was interested in a specific type of waterthey , which unlike igneous rocks do not crystallize at the surface but deep in the crust. A new analytical method has also been developed to study the composition of underground rock samples from and updates According to the tectonic deformation of this massive collision zone.
A coat more moisturizing than we thought
Thus the crystals of these rocks show much less signs of alteration than igneous rocks exposed to the elements at the surface. Their results eventually show that it is not 4, but more than 8% of the water (by weight) that the magma had before it crystallized.
These results also provide a better understanding of sediment formationor gone or which requires a large amount of water. 4% previously estimated was not sufficient to explain the formation From . The problem is now resolved. These ore deposits would thus be formed from volcanic fluids very rich in water (12 to 20%) which would have separated from the primary magma at the time of its crystallization. So understanding the generation of these superhydric rock fluids is of great interest to the search for new deposits.